Ford F750 with Caterpillar engine has no heat?

Ford F750 with Caterpillar engine has no heat? - 1
Added (1). Took off both heater hose lines and both have coolant flowing out of them. I think this is an issue but what is the cause?
Added (2). Thermostats seem ok. Coolant is full. Engine reaches normal operation temps of 180 range.
Added (3). Heater core is not restricted. The key here is I have hot coolant flowing out of BOTH heater lines going to the heater core. Should only have coolant flowing from one of them.

Read more: Ford F750 with Caterpillar engine has no heat?